Move extraction of linestrings out of QgsExpression file + add unit test

src/core/geometry/qgsgeometryutils.cpp

@@ -14,10 +14,52 @@ email                : marco.hugentobler at sourcepole dot com
  ***************************************************************************/
 
 #include "qgsgeometryutils.h"
+
+#include "qgscurvev2.h"
+#include "qgscurvepolygonv2.h"
+#include "qgsgeometrycollectionv2.h"
+#include "qgslinestringv2.h"
 #include "qgswkbptr.h"
+
 #include <QStringList>
 #include <QVector>
 
+QList<QgsLineStringV2*> QgsGeometryUtils::extractLineStrings(const QgsAbstractGeometryV2* geom)
+{
+  QList< QgsLineStringV2* > linestrings;
+  if ( !geom )
+    return linestrings;
+
+  QList< const QgsAbstractGeometryV2 * > geometries;
+  geometries << geom;
+  while ( ! geometries.isEmpty() )
+  {
+    const QgsAbstractGeometryV2* g = geometries.takeFirst();
+    if ( const QgsCurveV2* curve = dynamic_cast< const QgsCurveV2* >( g ) )
+    {
+      linestrings << static_cast< QgsLineStringV2* >( curve->segmentize() );
+    }
+    else if ( const QgsGeometryCollectionV2* collection = dynamic_cast< const QgsGeometryCollectionV2* >( g ) )
+    {
+      for ( int i = 0; i < collection->numGeometries(); ++i )
+      {
+        geometries.append( collection->geometryN( i ) );
+      }
+    }
+    else if ( const QgsCurvePolygonV2* curvePolygon = dynamic_cast< const QgsCurvePolygonV2* >( g ) )
+    {
+      if ( curvePolygon->exteriorRing() )
+        linestrings << static_cast< QgsLineStringV2* >( curvePolygon->exteriorRing()->segmentize() );
+
+      for ( int i = 0; i < curvePolygon->numInteriorRings(); ++i )
+      {
+        linestrings << static_cast< QgsLineStringV2* >( curvePolygon->interiorRing( i )->segmentize() );
+      }
+    }
+  }
+  return linestrings;
+}
+
 QgsPointV2 QgsGeometryUtils::closestVertex( const QgsAbstractGeometryV2& geom, const QgsPointV2& pt, QgsVertexId& id )
 {
   double minDist = std::numeric_limits<double>::max();

src/core/geometry/qgsgeometryutils.h

@@ -19,6 +19,8 @@ email                : marco.hugentobler at sourcepole dot com
 #include "qgspointv2.h"
 #include <limits>
 
+class QgsLineStringV2;
+
 /** \ingroup core
  * \class QgsGeometryUtils
  * \brief Contains various geometry utility functions.
@@ -30,6 +32,11 @@ class CORE_EXPORT QgsGeometryUtils
 {
   public:
 
+    /** Returns list of linestrings extracted from the passed geometry. The returned objects
+     *  have to be deleted by the caller.
+     */
+    static QList<QgsLineStringV2*> extractLineStrings( const QgsAbstractGeometryV2* geom );
+
     /** Returns the closest vertex to a geometry for a specified point
      */
     static QgsPointV2 closestVertex( const QgsAbstractGeometryV2& geom, const QgsPointV2& pt, QgsVertexId& id );

src/core/qgsexpression.cpp

@@ -29,6 +29,7 @@
 #include "qgsfeature.h"
 #include "qgsgeometry.h"
 #include "qgsgeometryengine.h"
+#include "qgsgeometryutils.h"
 #include "qgslogger.h"
 #include "qgsmaplayerregistry.h"
 #include "qgsogcutils.h"
@@ -1432,52 +1433,7 @@ static QVariant fcnSegmentsToLines( const QVariantList& values, const QgsExpress
   if ( geom.isEmpty() )
     return QVariant();
 
-  QList< QgsAbstractGeometryV2 * > geometries;
-
-  QgsGeometryCollectionV2* collection = dynamic_cast< QgsGeometryCollectionV2* >( geom.geometry() );
-  if ( collection )
-  {
-    for ( int i = 0; i < collection->numGeometries(); ++i )
-    {
-      geometries.append( collection->geometryN( i ) );
-    }
-  }
-  else
-  {
-    geometries.append( geom.geometry() );
-  }
-
-  QList< QgsLineStringV2* > linesToProcess;
-  while ( ! geometries.isEmpty() )
-  {
-    QgsAbstractGeometryV2* g = geometries.takeFirst();
-    QgsCurveV2* curve = dynamic_cast< QgsCurveV2* >( g );
-    if ( curve )
-    {
-      linesToProcess << static_cast< QgsLineStringV2* >( curve->segmentize() );
-      continue;
-    }
-    QgsGeometryCollectionV2* collection = dynamic_cast< QgsGeometryCollectionV2* >( g );
-    if ( collection )
-    {
-      for ( int i = 0; i < collection->numGeometries(); ++i )
-      {
-        geometries.append( collection->geometryN( i ) );
-      }
-    }
-    QgsCurvePolygonV2* curvePolygon = dynamic_cast< QgsCurvePolygonV2* >( g );
-    if ( curvePolygon )
-    {
-      if ( curvePolygon->exteriorRing() )
-        linesToProcess << static_cast< QgsLineStringV2* >( curvePolygon->exteriorRing()->segmentize() );
-
-      for ( int i = 0; i < curvePolygon->numInteriorRings(); ++i )
-      {
-        linesToProcess << static_cast< QgsLineStringV2* >( curvePolygon->interiorRing( i )->segmentize() );
-      }
-      continue;
-    }
-  }
+  QList< QgsLineStringV2* > linesToProcess = QgsGeometryUtils::extractLineStrings( geom.geometry() );
 
   //ok, now we have a complete list of segmentized lines from the geometry
   QgsMultiLineStringV2* ml = new QgsMultiLineStringV2();

tests/src/core/testqgsgeometryutils.cpp

@@ -16,11 +16,15 @@
 #include <QtTest/QtTest>
 #include <QObject>
 #include "qgsgeometryutils.h"
+#include "qgslinestringv2.h"
+#include "qgspolygonv2.h"
+#include "qgsmultipolygonv2.h"
 
 class TestQgsGeometryUtils: public QObject
 {
     Q_OBJECT
   private slots:
+    void testExtractLinestrings();
     void testCircleClockwise_data();
     void testCircleClockwise();
     void testAngleOnCircle_data();
@@ -41,6 +45,32 @@ class TestQgsGeometryUtils: public QObject
     void testAverageAngle();
 };
 
+
+void TestQgsGeometryUtils::testExtractLinestrings()
+{
+  QgsLineStringV2* outerRing1 = new QgsLineStringV2();
+  outerRing1->setPoints( QList<QgsPointV2>() << QgsPointV2( 1, 1 ) << QgsPointV2( 1, 2 ) << QgsPointV2( 2, 2 ) << QgsPointV2( 2, 1 ) << QgsPointV2( 1, 1 ) );
+  QgsPolygonV2* polygon1 = new QgsPolygonV2();
+  polygon1->setExteriorRing( outerRing1 );
+
+  QgsLineStringV2* outerRing2 = new QgsLineStringV2();
+  outerRing2->setPoints( QList<QgsPointV2>() << QgsPointV2( 10, 10 ) << QgsPointV2( 10, 20 ) << QgsPointV2( 20, 20 ) << QgsPointV2( 20, 10 ) << QgsPointV2( 10, 10 ) );
+  QgsPolygonV2* polygon2 = new QgsPolygonV2();
+  polygon2->setExteriorRing( outerRing2 );
+
+  QgsLineStringV2* innerRing2 = new QgsLineStringV2();
+  innerRing2->setPoints( QList<QgsPointV2>() << QgsPointV2( 14, 14 ) << QgsPointV2( 14, 16 ) << QgsPointV2( 16, 16 ) << QgsPointV2( 16, 14 ) << QgsPointV2( 14, 14 ) );
+  polygon2->setInteriorRings( QList<QgsCurveV2*>() << innerRing2 );
+
+  QgsMultiPolygonV2 mpg;
+  mpg.addGeometry( polygon1 );
+  mpg.addGeometry( polygon2 );
+
+  QList<QgsLineStringV2*> linestrings = QgsGeometryUtils::extractLineStrings( &mpg );
+  QCOMPARE( linestrings.count(), 3 );
+  qDeleteAll( linestrings );
+}
+
 void TestQgsGeometryUtils::testLeftOfLine_data()
 {
   QTest::addColumn<double>( "x" );